Mesoporous silica decorated with L-cysteine as active hybrid materials for electrochemical sensing of heavy metals

Abstract Detection of heavy metals using portable electrochemical devices will only become practical if advanced materials with selective interaction to metal ions are found. Mesoporous silica materials are already important performers in nanoscience and nanotechnology scene but they are not considered as active materials for electrochemistry applications. Here, electrochemical sensing of heavy metals is performed using chemically decorated mesoporous silica with L-cysteine (L-cys). Modified electrodes with L-cys/porous silica and square wave voltammetry (SWV) technique were applied for the simultaneous determination of cadmium ion (Cd2+) and lead ion (Pb2+). Two well-known mesoporous silica with honeycomb channel-like pores were used, SBA-15 and MCM-41. Parameters as surface area, pore volume, and average pore size are correlated with the efficiency of electrochemical sensors. Cd2+ and Pb2+ sensors exhibit outstanding results with considerable low detection limit from SBA-15/L-cys (0.22 µg.L-1 for Cd2+ and 0.36 µg.L-1 for Pb2+) and MCM-41/L-cys (0.23 µg.L-1 for Cd2+ and 0.76 µg.L-1 for Pb2+). Pore size appears to be the most relevant feature for heavy metal detection and the SBA-15/L-cys, which has large pores, performed better than MCM-41/L-cys regarding detection limit.